1. Field of the Invention
This invention relates to fluorosilicone lubricant compositions. More particularly, this invention relates to fluorosilicone lubricants exhibiting excellent lubricating properties in addition to a high level of resistance to heat or cold.
2. Background Information
Silicone lubricants based on dimethylsilicone oil or methylphenylsilicone oil have a resistance to heat and cold in addition to friction properties that are superior to those of organic oil-based lubricants. For example, the dynamic coefficient of friction for dimethylsilicone oil-based silicone lubricants is 0.2 For these reasons silicone lubricants are used in a variety of applications.
The last few years have seen a number of proposals with regard to the blending of heat stabilizers into the these silicone lubricants for the purpose of improving their heat resistance. Thus, for example, Japanese Patent Application Laid Open [Kokai or Unexamined] No. Sho 51-41046 [41,046/1976 ] teaches adding the reaction product obtained from cerium chloride and an alkali metal silanolate that contains at least 3 organosiloxane units, while Japanese Laid Open Patent application No. Sho 60-106891 [106,891/1985] proposes the addition of an organopolysiloxane containing the anilinophenoxy or naphthylaminophenoxy group.
On the other hand, fluorosilicone lubricants based on 3,3,3-trifluoropropyl-containing silicone oils have a solvent resistance and boundary lubricating characteristics superior to those of the heretofore known silicone lubricants and as a result are used as lubricants in specialty applications.
However, the above-described fluorosilicone lubricants have a poor heat resistance. Thus, when subjected to use at elevated temperatures, the 3,3,3-trifluoropropyl-containing silicone oil depolymerizes, resulting in a substantial deterioration in the lubricating properties of this type of fluorosilicone lubricant. In response to this, Japanese patent application Laid Open No. Hei 3-143997 [143,997/1991] discloses a fluorosilicone lubricant that consists of 3,3,3-trifluoropropyl-containing silicone oil and the anilinophenoxy(or naphthyl aminophenoxy)-containing organopolysiloxane proposed in Japanese Patent Application Laid Open Number Sho 60-106891.
The fluorosilicone lubricant proposed in Japanese Patent Application Laid Open Number Hei 3-143997 still has an unsatisfactory heat resistance. Moreover, the heat resistance also remains inadequate in the case of fluorosilicone lubricant consisting of 3,3,3-trifluoropropyl- containing silicone oil and he reaction product proposed in Japanese Pa-tent Application Laid Open No. Sho 51-41046.
With the goal of further improving the lubricating properties of silicone lubricants, a number of silicone lubricants thickened with fluororesin powder (e.g., polytetrafluoroethylene powder, etc.) have been proposed over the course of the last few years (Japanese Patent Application Laid Open [Kokai or Unexamined] Nos. Sho 54-163277 [163,277/1979], Sho 54-49460 [49,460/1979 ], Sho 57-34135 [34,135/1982], and Sho 62-190290 [190,290/1987]).
Fluorosilicone lubricants composed of this type of silicone oil and a thickener have an excellent oil resistance, excellent load-bearing capacity at heavy loads, and excellent boundary lubrication properties. A disadvantage of these fluorosilicone lubricants is their poor resistance to cold temperatures. Thus, they suffer from a substantial deterioration in lubricating performance when used at these temperatures, which prevents their use at low temperatures to lubricate machine elements sliding at high speeds.
One objective of this invention define a class of silicone lubricants that exhibit an excellent resistance to either heat or cold and excellent lubricating properties.